Plastic and viscous material mixing device



Nov. 17, 1942. A. L STONE PLASTICND vscous MATERIAL MIXING DEVICE INVENToR //en L. ifo/ve Filed March 23,` 1940 ATTO R N EY Patented Nov. 177, 1942` PLASTIC AND VISCOUSI MATERIAL MIXING DEVICE Allen L. Stone, Los Angeles, Calif., assignor to Pneumastic Co. Inc., Los Angeles,`C1alif.,`a corporation of Nevada Application March3, 1946,7Serial No. 325.5179

claims.

Thisinvention relates to a device for mixing viscousand plastic materials-in which the various ingredients, such as the binding agent and the aggregate, are conveyed in measured amounts to a mixing passage Where the mixing operation is. performed. 'Moreparticularly it relates to a device of the character referred to which is vespecially useful for mixing aggregate and viscous binding materialsuch as emulsied asphalt, petroleum base asphalt or` coal tar products, and for applying the mixture to adesired surfacewhich is tobe coated. A mixing device of this general character is'disclosed in my copending application Serial No..203,077, filed April 20, 1938, for Plasticmaterial mixing device, new Patent No. 2,213,640.

It is a general object of the invention to provide -an improved device for mixing viscous or plastic materials with an aggregate for application to a surface to be coated.

Another object of the invention is to provide mixing apparatus of the character referred to which can handle a wide range of sizes of aggregate in performing the mixing operation.

Another object of the invention is to provide an improved mixing passage construction wherein a more ecient mixing operation is performed than in similar passages heretofore provided.

Another object of the invention is to provide an improved method of constructing a resilient mixing device to enhance the .operating characteristic thereof as well as to provide for economical Y manufacture.

Other objects and advantages of the invention Will be apparent fromithe'following description of a preferred embodiment thereof as illustrated in the accompanying drawing, in which:

Figure 1 is a longitudinal sectional View through a mixing device embodying my inven- .of the wall of the mixing passages in the resilient body.

Generally the mixing device rof my invention comprises a resilient body, preferably of elonpgated form and yhaving, a longitudina1 mixing ',.passage formed therein,.which is ofy a tortuous or :.zigzag character'andY has alternate enlargements 55 `of Va binding'materialesuch as emulsi-fied.A asphalt,

.and restrictions sothatthe material laden air stream will be alternatelyexpanded and compressed `while changing its direction of movement `as it flows through the -.passageVso as to lrepeatedly strike and rebound from the resilient Walls defining the passage. -Measured amounts of both the aggregate and @the .binding materials such as emulsied asphalt are suppliedto a feed y chamber under considerable pressureand as lthey pass ythrough the mixing passage apulsating-action is set up which tends to further'facilitate the rebound and mixing action of thermaterials as they travel through the passage.

lReierringfto Figures land 2 the vmixer may comprisean elongated casing I0 which may -have a plurality of apertures Il .for a purpose later described. Within Vthe casing I0 an elongated resilientebody I2 may be provided which is preferably molded of rubber `as describedin detail hereinaiter. Body I2 has a feed chamber .I3 at one end and a discharge tube orv throat I4 at the other end extending beyonda shoulder I6 ofthe body I2. The discharge tube I4 may be positioned within the casing I0 by means of ringlike collar I1 ofresilientmaterial which is secured as by-boltsl 8 against an inturnedilange I9 of the casing II). Collar I'I also provides for lateral flexing movement to accommodate a certain amount of limited endwise .movement of discharge tube I4. e

At its feedend the body I 2 has its end'disposed within a cup-shaped end plate orcollar 20 slidably disposed within the end of the casing I-and adapted for movement relative theretoto permit limited velongation andcontractionfof the resilientbody I2. Spring `2I seats against the end of collar 20 and fan adjustable collar 22 slidably engagedabout casing IB. To limit the positioning of collar 22under the iniiuence of spring 2|, adjusting bolts r23 m-ay be provided which extend through bosses .24 on collar 22 and have their heads engaged with apertured ears 25 ,on casing I'. If desired, a recoil spring 23a may be-.placed around bolts 23 between each bossf24and the aligned ear/25.

To'provideior feeding of material to the chamber I 3,'*the resilient body I2 mayhavemold'ed or Aotherwisev suitably vsecured therein a threaded feed 'tube 26 Whichis secured to collar 20.,.by suitable lock nuts and which discharges vsubstantially lengthwiserof thecasing. For example, tube 26 may be used to `feed aggregate` carried by lan air stream through a suitable `feed hose (not -;shown). VTo lprovide for introduction vided with a lighter re-enforcing as a second feed tube 21 is provided which leads to a self-closing nipple-type nozzle 21a, having its end walls slotted in two planes at right angles to form the segments of the nipple. The nozzle 21a opens generally downwardly toward the bottom wall of the chamber I3 to intersect the path of discharge from aggregate feed tube 26.

As seen-in Figure 1,-- the body I2 is provided with a tortuous mixing passage which in the embodiment illustrated has a substantially constant dimension in the plane of Fig. 1. direction at right angles to the plane of Fig. 1, as seen in Fig. 2, the walls of the passage alternately approach and recede to form successive mixing chambers 28 which are separated by restricted passages or restrictions 29. Similarly the outer walls of the body I2 have the same tortuous shape and alternately contact and recede from the casing I8. Thus, the body I2 is free to move with reference to the casing both as to elongation and as to lateral expansion. As pointed out later, in operation an actual pulsation of the body I2 is Set up to facilitate the mixing action by constant motion of the walls surrounding the elongated passage.

In order to facilitate the dispersing and mixing operation dispersing or defiecting means may be provided in the passage in the form of integrally molded buttons 3| which are of rounded contour and are disposed in opposed relation in the feed chamber I3 and in the respective mixing chamber 28 as seen most clearly in Fig. l.

To insure sealing of the rubber body I2 and to provide a controlled expansion thereof, the body I2 is formed of an inner portion 32 wh1c h is molded and an outer covering 33 which 1s vulcanized thereon. After molding the core mal7 be removed from body, I2 by sealing one end thereof and then expanding the body to facilitate withdrawal of the core. The expansion may be accomplished by forcing grease ,or some other suitable material into the mixing passage under pressure.

. In order to facilitate and control the pulsating action of the body at various points along its length, the outer covering is formed with a varying thickness along the mixing passage, with the thickness reducing generally from the feed and to the discharge end of said passage. Preferably the covering at 33a about the feed chamber I3 is of substantial thickness as compared to other portions of said co ering indicated at 33D and 33o.

In practice the re-enforcing may be effected and controlled by winding pure gum rubber strips about the body I2 to provide a different number of layers at desired locations therealong. Usually the entire body will be covered with a single layer of sealing rubber, while additional re-enforcing is provided as may be desired. As shown, the heaviest re-enforcing is provided along the feed chamber I3 and the first mixing chamber 28, the second mixing chamber 28 is provided with a medium amount of re-enforcing, indicated at 33e, and the nal mixing chamber 28 is proindicated at 33D. After the gum rubber strips are wound about the body, the assembly is placed in a suitable fixture and a Vulcanizing operation is performed to provide an integral bond between the rubber re-enforcing strips and the molded portion 32 of the body I2.

In actual practice, resilient bodies have been madewwherein a wall thickness andre-enforcing isv providedwhich will resist an expansion pres- Ina sure up to substantially lbs/sq. inch at the feed chamber, 40 lbs/sq. in. in the second chamber 28, and 20 lbs/sq. in. in the final mixing chamber 28, and the discharge tube. If desired, the re-enforcing of the restrictions 29 may be controlledv to resist expansion under pressure up to 60 lbs/sq. in. at the first and 30 lbs/sq. in. at the second.

Means may be provided for enabling adjustable restrictions in the passage means, and for this Purpose leaf springs 36 (Fig. 1) may be provided having curved ends 31 engaging body I2 at the fiat side of a pair of adjacent mixing chambers 28. Each spring 36 may be carried by a screw 39 engaging a threaded fitting 4I mounted in the Wall of casing IIJ. A suitable lock-nut may be associated with each spring. As shown, two sets of passage restricting means may be provided. The ends of springs 36 are engaged with the wall portions having buttons 3| and adjustment of springs 36 may be made to engage the opposed buttons 3l in the second mixing chamber 28 as indicated in dotted lines in Figure 3. With such restriction to form a divided mixing chamber, the combined cross-sectional areas of the divisions thereof are still greater than the cross-sectional area of a restriction 29.

In operation, for example, for mixing a viscous material such as emulsied asphalt with an aggregate, a metered amount of lthe emulsifiedasphalt may be supplied through the fitting. 26 under a pressure of say lbs. per square inch while the aggregate may be introduced through the fitting 21 in an air streamV having a presr sure of say 60 lbs/sq. inch. The aggregate may range in size from 200 mesh screenings up to pieces having a diameter of 1/2" to 3A".

The stream of binder, such as emulsifled asphalt, from the nozzle 21a. will enter the feed chamber I3 and cross the stream of air and aggregate from the feed fitting 26, so that the mixed streams will impinge against the lower wall of the feed chamber to rebound with a swirling action within such feed chamber. This first phase of the mixing action which occurs in the feed chamber and the first mixing chamber 28, which opens into such feed chamber without restriction, may be said to be an expanding phase wherein the two streams of material are ejected from confined passages under pressure into the larger feed chamber to expand as they enter such feed chamber. The reinforcing of the feed chamber I3 would be selected so as to prevent expansion thereof under a selected pressure, say 80 pounds per square inch.

The material in passing from the feed chamber I3 into the first mixing chamber 28 must change its direction and at the same time it encounters the two dispersing buttons 3| in such chamber to be further broken up and intermingled thereby. It will be noted that as the material leaves the feed chamber I3 and passes into Vthe first mixing chamber 28, the cross-sectionaly area of the mixing passage will gradually decrease until the. first restriction or throat 29 is encountered.

Because of the restriction provided at the throat 29, the pressure will be built up at this throat until itis relieved by the expansion thereof permitted by the free space 42 around the first throat 29. The pulsating action caused by successive building up and relief of pressure at the rst throat 29 occurs rapidly so that the walls of the throat pulsate or vibrate in a very rapid manner. Thus, the second phase of the mixing action is a restriction of the material in space of smaller cross-sectional area, while at the same time the direction of'ilow of the material is again changed as the material leaves the rst restriction or throat 2S. As the material leaves the throat it virtually explodes as it rapidly expands in entering the second mixing chamber 28.

It will be noted that no jamming can occur at the restriction 29 because of the free expansion provided thereby, so that larger pieces of aggregate will be freed and carried on through the mixing chamber. Again in the second mixing chamber 2li the material encounters a pair of dispersing buttons 3| to enhance the dispersion and to promote intimate intermingling of the materials.

The second chamber 23 is provided with a reenforcing thereabout to prevent expansion, say up to 40 lbs. of pressure, and from this mixing chamber the material must proceed through the second restriction 29 having a lesser amount of re-enforcing, say for 30 lbsf/sq. in. pressure. A pulsation will also be set up at this point causing rapid rebounding and intermingling of the material passing therethrough. From the second Vrestriction 29, material in substantiallyV mixed condition expands into the last mixing chamber At8, where again a pair of dispersing buttons 3| perform a further dispersing action and the final mixing is eiected with each particle of aggregate thoroughly coated with the binder. The mixed material is discharged under considerable pressure through discharge outlet i4 in the form of a substantially continuous, homogeneous stream o1' l spray for impact application to the surface to be coated. The discharge tube l can expand into the space thereabout to prevent jamming of pieces of aggregate such as small rock in this location.

l In the event of heavy feeding of material under high pressure the entire body I2 can elongate against the pressure of spring 2 l, and the amount of such elongation can be controlled by adjusting spring 2|. The length of the passage is determined by the character of the material to be mixed and the use for which it is intended, as well as the desired constituency of the discharged product. For thinner mixes a shorter passage may be employed as well as where considerable pressure is desired for application. For materials requiring a longer mixing action or for heavier materials a longer passage may be used. Adjustment of spring 2| to lengthen or shorten the space occupied by the resilient body also decreases or increases the angularity of the direction change of the material in passing from chamber to chamber.

It is to be noted that adjustment of springs 4| also serves to change the character of the mixing chambers by varying the sp-acing between the opposed dispersing buttons 3|. For example, as shown in dotted lines in Figure 3 the buttons 3| may be adjusted to engage each other and thereby divide the mixing chamber. Generally, for mixing with light viscous liquids with a high setting power, a minimum or no spring pressure is employed and the passage is left open to its greatest extent and a high aggregate pressure is employed. With heavier viscosities and slower setting up characteristics, a lower aggregate pressure is used and the flow restricted by increasing the pressure of springs 3S.

The pulsating action referred to is controlled both by controlling the passage restriction by use of springs 36, by varying the elongation characteristics by changing the compression of spring 2|, and by varying the pressures on the binder` and aggregate materials. In general, adjustment should be made'to build up pressures and restrict the flow where vigorous pulsating action is desired.

I claim:

1. A plastic and viscous material mixing device comprising a casing, a resilient body mounted in said casing having a tortuous passage extending therethrough, said tortuous passage having alternate enlargements and restrictions therein, and the discharge end of said passage comprising a resilient discharge tube projecting from said casing, said body having portions engaging said wall and other portions spaced therefrom to enable expansion and contraction of the body, and a resilient collar positioning said tube with respect to said casing.

2. A plastic and viscous material mixing device comprising a casing, a resilient body mounted in said casing having a tortuous passage extending therethrough, said tortuous passage having alternate enlargements and restrictions therein, the discharge end of said passage comprising a resilient expansible tube projecting from said casing, said body having portions engaging said wall and other portions spaced therefrom to enable expansion and contraction of the body, a resilient collar positioning said tube with respect to said casing, and yieldable means interposed between an end of said body and the adjacent end of said casing providing for velongation of said -body within saidl casing.

3, A plastic and viscous material mixing device comprising a oasing,-a resilient body mounted insaid casing having a tortuous passage extending therethrough, said tortuous passage having alternate enlargements and restrictions therein, said body having portions engaging said wall and other portions spaced therefrom to enable expansion and contraction of the body, and yieldable means interposed between an end of said `body and the adjacent end of said casing providing for elongation of said body within said casing.

4. A plastic and viscous material mixing device comprising an elongated casing, an elongated resilient body mounted in said casing having a tortuous mixing passage extending therethrough, said body being free for elongation and contraction during a mixing operation, and adjustable means for compressing said body length- Wise in said casing,

5. A plastic and viscous material mixing device comprising an elongated casing, an elongated resilient body mounted in said casing having a tortuous mixing passage extending therethrough, said body being free for elongation and contraction during a mixing operation, and adjustable means for yieldably resisting elongating movement of said body.

6. A plastic and viscous material mixing device comprising a casing, a resilient body mounted in said casing having a tortuous passage extending therethrough, said tortuous passage having a plurality of mixing chambers separated by restrictions, and material dispersing means in opposed relation upon opposite walls of said mixing chambers, said dispersing means comprising opposed rounded buttons projecting inwardly from opposed walls of each of said chambers.

7. A plastic and viscous material mixing device comprising a casing, a resilient body mounted in said casing having a tortuous mixing passage extending therethrough, said tortuous passage having alternate enlargements and restrictions thereiny and resilient re-enforcing means about the said body providing for different exing alternate enlargements and restrictions pansion pressures for said restrictions and said therein, and said body alternately engaging and enlargements. 5 receding from said casing, the discharge end of 8. A plastic and viscous material mixing de- 't said passage comprising a normally open throat vice comprising a casing, a resilient body mountwhich is capable of expansion to pass an obed in said casing having a tortuous mixing passtruction, and yieldable means for positioning sage extending therethrough, said tortuousY passaid throat With respect to said casing, said ed in said casing having a tortuous passage e'x'- tending therethrough, said tortuous passage hav'- vsage having alternate enlargements and restric- 1,0 means being yieldable axially of said casing to vprovide for expansion and constraction ot saidv body, and said body being formed to provide dif- .ing formed to provide difierent expansion prestions therein, said body being constructed to provide for diierent expansion pressures along said body with said pressures decreasing from the feed end of said passage to the discharge end 13. A plastic and viscous material mixing dethereof. 1,5 vice comprising a casing, a resilient body mount- 9. A plastic and viscous material mixing de' ed in said casing having a tortuous passage exvice comprising a casing, a resilient body mounttending therethrough, said tortuous passage ed in said casing having a tortuous mixing pashaving alternate enlargements and restrictions sage extending therethrough, said body also betherein, and said body alternately engaging and ing spaced from said casing at various points to,.20 receding from said casing, the discharge end of said passage comprising a normally open throat capable of expansion to pass an obstruction, ferent expansion pressures along said passage. yieldabie means supporting said throat with re- 10. A plastic and viscous material mixing despect to said casing, and resilient means for convice comprising a casing, a resilient body mount 2 5 trolling longitudinal expansion and contraction ed in said casing having a tortuous mixing pas` of said body Within said casing. sage extending therethrough, said passage hav- 14. A resilient mixing member having a toring a series or" mixing chambers separated by retuous passage extending therethrough, said passtrictions, said body also being spaced from said sage having successive enlargements and restriccasing at various points to provide for expansionY 30 tions therein, which comprises a molded body and contraction of said body, and said body beportion of resilient material such as rubber, and a covering of a rubber material disposed about sures along said passage and with the smaller said body portion, said covering having alternatexpansion pressures at said restrictions. ing portions of varying thicknesses along said l1. A plastic and viscous material mixing de- 35 body portion to obtain desired Wall strengths of permit contraction and expansion of said body and being yieldable radially of said casing to a1- loW expansion for an obstruction.

vice comprising a casing, a resilient body mounted in said casing having a tortuous mixing passage extending therethrough, said passage having a series of chambers separated by restrictions, said body also being spaced from said cas- 40 ing at various points to provide for expansion and contraction of said body, and said body being formed to provide different expansion pres- -sures along said passage with the expansion pressures of the chamber walls decreasing suc-y .45

cessively from the feed to the discharge end of said passage, the expansion pressures of said restrictions being the order of the pressure at the discharge end of said passage,

12. A plastic and viscous material mixing de- 5 vice comprising a casing, a resilient body mountvarying amounts with the thicker portions encompassing the passage enlargements, the covering material being bonded to the body portion.

15. A resilient mixing member having a tortuous passage extending therethrough, which comprises a molded body portion of a resilient material such as rubber, and a covering of sheet rubber material disposed about said body portion to provide alternating portions of varying Wall thicknesses along the passage with the thickness of the thicker portions decreasing from the feed end toward the discharge end of said member, the covering material being bonded to the body portion.

ALLEN L. STONE. 

